Aneuploid embryonic stem cells drive teratoma metastasis.

Aneuploidy, a deviation of the chromosome number from euploidy, is one of the hallmarks of cancer. High levels of aneuploidy are generally correlated with metastasis and poor prognosis in cancer patients. However, the causality of aneuploidy in cancer metastasis remains to be explored. Here we demonstrate that teratomas derived from aneuploid murine embryonic stem cells (ESCs), but not from isogenic diploid ESCs, disseminated to multiple organs, for which no additional copy number variations were required. Notably, no cancer driver gene mutations were identified in any metastases. Aneuploid circulating teratoma cells were successfully isolated from peripheral blood and showed high capacities for migration and organ colonization. Single-cell RNA sequencing of aneuploid primary teratomas and metastases identified a unique cell population with high stemness that was absent in diploid ESCs-derived teratomas. Further investigation revealed that aneuploid cells displayed decreased proteasome activity and overactivated endoplasmic reticulum (ER) stress during differentiation, thereby restricting the degradation of proteins produced from extra chromosomes in the ESC state and causing differentiation deficiencies. Noticeably, both proteasome activator Oleuropein and ER stress inhibitor 4-PBA can effectively inhibit aneuploid teratoma metastasis.

Single-cell transcriptomics links malignant T cells to the tumor immune landscape in cutaneous T cell lymphoma.

Cutaneous T cell lymphoma (CTCL) represents a heterogeneous group of non-Hodgkin lymphoma distinguished by the presence of clonal malignant T cells. The heterogeneity of malignant T cells and the complex tumor microenvironment remain poorly characterized. With single-cell RNA analysis and bulk whole-exome sequencing on 19 skin lesions from 15 CTCL patients, we decipher the intra-tumor and inter-lesion diversity of CTCL patients and propose a multi-step tumor evolution model. We further establish a subtyping scheme based on the molecular features of malignant T cells and their pro-tumorigenic microenvironments: the TCyEM group, demonstrating a cytotoxic effector memory T cell phenotype, shows more M2 macrophages infiltration, while the TCM group, featured by a central memory T cell phenotype and adverse patient outcome, is infiltrated by highly exhausted CD8+ reactive T cells, B cells and Tregs with suppressive activities. Our results establish a solid basis for understanding the nature of CTCL and pave the way for future precision medicine for CTCL patients.

A body map of somatic mutagenesis in morphologically normal human tissues.

Somatic mutations that accumulate in normal tissues are associated with ageing and disease1,2. Here we performed a comprehensive genomic analysis of 1,737 morphologically normal tissue biopsies of 9 organs from 5 donors. We found that somatic mutation accumulations and clonal expansions were widespread, although to variable extents, in morphologically normal human tissues. Somatic copy number alterations were rarely detected, except for in tissues from the oesophagus and cardia. Endogenous mutational processes with the SBS1 and SBS5 mutational signatures are ubiquitous among normal tissues, although they exhibit different relative activities. Exogenous mutational processes operate in multiple tissues from the same donor. We reconstructed the spatial somatic clonal architecture with sub-millimetre resolution. In the oesophagus and cardia, macroscopic somatic clones that expanded to hundreds of micrometres were frequently seen, whereas in tissues such as the colon, rectum and duodenum, somatic clones were microscopic in size and evolved independently, possibly restricted by local tissue microstructures. Our study depicts a body map of somatic mutations and clonal expansions from the same individual.

Organ and tissue-specific distribution of selected polycyclic aromatic hydrocarbons (PAHs) in ApoE-KO mouse.

Polycyclic aromatic hydrocarbons (PAHs) are one of the most prevalent classes of environmental pollutants resulting from the incomplete combustion of hydrocarbons. Exposure to PAHs is implicated in the pathogenesis of the cardiovascular disease, pulmonary disease, and even cancer. However, little is known about organ- and tissue-specific distribution patterns of PAHs in animals at macro-tissue and microscopic levels. Here, by combining GC-MS and single-molecule fluorescence microscopy (SMFM), we revealed the distribution characteristics of four different PAHs (phenanthrene (Phe), pyrene (Pyr), perylene (Per), and benzo[a]pyrene (BaP)) in atherosclerosis model mice (ApoE-KO mice) at macro-tissue and micro-region level after long-term oral exposure. Average PAH concentrations detected by GC-MS in seven tissues ranged from 6.44 to 441 ng/g. The gastrointestinal tract, epididymal fat pat, and lung accumulated higher levels of PAHs, whereas relatively lower PAH residuals were found in the liver, brain, and kidney. Correlation analysis showed that PAHs with higher molecular weight (r: -0.972 to -0.746), Log Kow (r: -0.984 to -0.746) and lower water solubility (r: 0.720 to 0.994) were less prone to bioaccumulate. For the first time, SMFM demonstrated a distinct heterogeneous distribution of Per in the tissue slices. More interestingly, we observed many micro-cluster regions, namely hotspots, showed much higher Per fluorescent intensity than the other common regions. In the area of atherosclerotic plaque, the Per hotspots were colocalized with the micro-regions with the most severe inflammatory response. The hotspots with very high enrichment in PAHs were likely to stimulate the local inflammation and cause excessive damage of the aorta, which resulted in a significant increase of the relative area of atherosclerosis lesion and aggravated atherosclerosis, as observed in PAH exposed mice.

Macroscopic somatic clonal expansion in morphologically normal human urothelium.

Knowledge of somatic mutation accumulation in normal cells, which is essential for understanding cancer development and evolution, remains largely lacking. In this study, we investigated somatic clonal events in morphologically normal human urothelium (MNU; epithelium lining the bladder and ureter) and identified macroscopic clonal expansions. Aristolochic acid (AA), a natural herb-derived compound, was a major mutagenic driving factor in MNU. AA drastically accelerates mutation accumulation and enhances clonal expansion. Mutations in MNU were widely observed in chromatin remodeling genes such as KMT2D and KDM6A but rarely in TP53, PIK3CA, and FGFR3 KMT2D mutations were found to be common in urothelial cells, regardless of whether the cells experience exogenous mutagen exposure. Copy number alterations were rare and largely confined to small-scale regions, along with copy-neutral loss of heterozygosity. Single AA-associated clones in MNU expanded to a scale of several square centimeters in size.

Single-Cell Real-Time Visualization and Quantification of Perylene Bioaccumulation in Microorganisms.

Bioaccumulation of perylene in Escherichia coli and Staphylococcus aureus was visualized and quantified in real time with high sensitivity at high temporal resolution. For the first time, single-molecule fluorescence microscopy (SMFM) with a microfluidic flow chamber and temperature control has enabled us to record the dynamic process of perylene bioaccumulation in single bacterial cells and examine the cell-to-cell heterogeneity. Although with identical genomes, individual E. coli cells exhibited a high degree of heterogeneity in perylene accumulation dynamics, as shown by the high coefficient of variation (C.V = 1.40). This remarkable heterogeneity was exhibited only in live E. coli cells. However, the bioaccumulation of perylene in live and dead S. aureus cells showed similar patterns with a low degree of heterogeneity (C.V = 0.36). We found that the efflux systems associated with Tol C played an essential role in perylene bioaccumulation in E. coli, which caused a significantly lower accumulation and a high cell-to-cell heterogeneity. In comparison with E. coli, the Gram-positive bacteria S. aureus lacked an efficient efflux system against perylene. Therefore, perylene bioaccumulation in S. aureus was simply a passive diffusion process across the cell membrane.